Amphibians Vs. Reptiles : Similarities and Differences

Last Updated: Jan 19, 2017

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Difference between amphibians and reptiles: Among the animals in the animal kingdom, amphibians and reptiles are the most frequently interchanged. But did you know that even at early 1800, there had already been studies showing that the two are of different classes?

A zoologist named Josephus Nicolaus Laurenti termed “Reptilia” as a separate division from “Amphibia“. Since then, it became clearer that they are different in many aspects. Let’s explore the difference between amphibians and reptiles and also similarities between them in this article.

What Are Amphibians?

The word “amphibia” refers to a “double life” which in turn refers to the ability of the members of Class Amphibia to live both in water and on land. Basically, the Class Amphibia is composed of three orders: Anura (includes frogs and toads), Urodela (includes salamanders), and Apoda (caecillians).

Amphibians are unable to regulate their body temperature.

After hatching from eggs, they undergo through a larval stage which can range from just 10 days up to 20 years (for some species)!

During their larval stage, amphibians breathe through their gills but later on develop their lungs as they move on to land.

What Are Reptiles?

Basically the word reptile came from the Latin word “repere“ which means “to crawl” which is basically one characteristics of reptiles. As far as biologists are concerned, the main distinguishing characteristic of the members of Class Reptilia (reptiles) is that they are covered with hardened scales that act as defense and prevents further dehydration.

Most reptiles live in warm habitats like in deserts because they need the heat in order to keep themselves warm.

As compared to amphibians and lower animal forms, they have larger brains and thus better intellectual capacity.

Reptiles, excluding turtles and crocodiles, have both nostrils and a specialized structure called the Jacobson’s organ. This organ is very sensitive to chemical stimuli and is highly adapted to smelling.

The Evolution Of Amphibians And Reptiles

In a gross oversimplification of the evolution of vertebrates, fish developed limbs to become tetrapods (animals with four limbs) that resided the land. These tetrapods include succeeding organisms like amphibians, reptiles, birds, and mammals.

The first amphibians have developed true legs and spent time on land after their early larval stage spent in water.

By living on land, amphibians are able to acquire more food as there is less competition. However, one downside of this is that their skin must always be kept moist, hence, they have to go back to water from time to time.

An organism called the SeymouriaSeymouria is known to be the connecting link between amphibians and reptiles. This animal exhibit both the skull properties of amphibians and the skeletons of reptiles. Aside from that, it had a hard outer armor and overlapping scales.

During the evolutionary process, reptiles evolved from amphibians and became the first true terrestrial vertebrates. The change of environment from aquatic to seemingly dry land required reptiles to adapt themselves.

From amphibians who previously were laying jelly-like eggs, reptiles had to lay them in shells for better chances of survival.

Similarities Between Amphibians And Reptiles

Because of fossils, it has already been proven by science that reptiles evolved from amphibians over 50 million years ago, hence both share similarities in so many ways. Listed below are some of them:

Able to exhibit camouflage (altering skin color to adapt to the environment), and mimicry (altering overall appearance to look like dangerous plants or animals).

Cloacal Anatomy

Both have the cloaca, an opening that serves as an opening for genital, intestinal, and urinary outlet.

Nervous System

Rely on spinal segmental reflexes for locomotion.

Difference Between Amphibians And Reptiles

While it has been said earlier that reptiles typically have evolved from amphibians, certain environmental factors on land had prompted reptiles to diverge from amphibians. They had to develop novel features that would ensure their survival and hence become different from amphibians. Listed below are these differences:

Features

Amphibians

Reptiles

Origin

First evolved about 370 million years ago.

First evolved 315 million years ago.

Habitat

Live in aquatic environments during their larval stage but migrate to the land during adulthood.

Most reptiles live on land but some species (like turtles, crocodiles, and alligators) can thrive underwater.

Mode of Respiration

Breathe through gills and lungs.

Breathe through lungs only.

Life Cycle

Undergo metamorphosis; during their larval stage, they breathe water using their gills but develop lungs (breathe air) in adulthood.

No larval stage, the young is a miniature version of the adult.

Vision

Have colored visions but is restricted only to a narrow bands of the color spectrum.

Generally adapted to daylight and can distinguish a wide variety of colors.

Circulatory System

Have three-chambered hearts.

Have three-chambered hearts but the ventricle is divide by a partial septum.

External Integument

Smooth, moist, and have sticky mucus.

Dry and full of scales made up of a protein called keratin.

Defense Mechanism

Secretion of toxins through the skin.

Have hard scales and an overall body armor; can also produce toxins through nails and teeth.

Appendages

Forelimbs are short while hind limbs are long and highly muscular. They also have webbed digits.

Usually have four equally sized limbs but some species (like snakes) have none.

Mode of Fertilization

External

Internal

Mode of Reproduction

Oviviparity (embryos develop inside the eggs but stay inside the mother’s body until they are ready to be hatched).

Oviparity (embryos found inside the eggs develop and eventually hatch outside the mother’s body); some species exhibit viviparity (embryos are gestated inside the mother’s body.

Eggs

Embryos are contained within soft and gel-like eggs and are considered to be anamniotic; They are laid in damp places or directly in the water surface.

Reptilian eggs are considered to be “amniotic eggs” which have hard and leathery outer shells; They are laid on land and is kept in warm places until hatched.

Examples

Frogs, toads, salamanders.

Lizards, snakes, turtles, crocodiles, alligators.

After all what is said, can you now accurately see the difference between amphibians and reptiles?